Study on Adsorption of Elemental Mercury in Coal-fired Flue Gas by Modified Activated Carbons

汞是煤中的痕量元素之一，其随着煤的燃烧释放到大气中。由于汞污染物具有较强的生理毒性和生物累积性，所以其污染控制受到了人们的普遍关注。我国作为以煤为主要能源结构的国家，对燃煤电站汞的排放控制研究刻不容缓。 本研究以目前燃煤烟气汞污染控制的主流吸附剂——活性炭为对象，从活性炭表面官能团出发，采用高温惰性氛围加热法去除活性炭表面所有酸性含氧官能团，继而通过化学浸渍法制备改性样品。通过吸附实验，研究改性前后样品的物理化学性质对Hg0吸附的影响，并建立了活性炭固定床吸附Hg0的简单数学模型。研究的主要内容和结果如下： (1)改性样品的制备 通过惰性氛围高温热处理去除活性炭表面的官能团，在此基础上采...Mercury is one of trace elements in coal, it is emitted into the atmosphere during the coal combustion process. Mercury control is arosed great attention because of its high physiological toxicity and bioaccumulation. Coal is the major energy source in China, so the control of mercury emission from coal-fired power plants demands immediate actions. This research is focused on activated carbons wh...学位：工学硕士院系专业：海洋与环境学院环境科学与工程系_环境工程学号：2262006115237

Study on the Mercury Emission From Seawater for Coal-fired Flue Gas De-sulphurization During Aeration Process

作为湿法脱硫工艺的吸收剂,海水在去除烟气中SO2的过程中,也能吸收烟气中的二价汞,但在恢复水质的曝气过程中,已吸附在海水中的二价汞易释放出来。该文采用金丝捕汞法富集曝气池上空大气中的汞,同时采集曝气池海水水样,考察不同运行工况下脱硫海水中的汞向大气释放的浓度水平及变化趋势。结果表明:曝气池上空总气态汞(TOTAl gASEOuS MErCury,TgM)的浓度平均值为10.01ng/M3,高出当地背景值的20倍以上。曝气池上空TgM浓度与池中海水的汞浓度、曝气强度呈正相关性。TgM浓度在白昼时段高于夜间时段,并在中午日光照射较强的时段出现峰值,表明光致还原对曝气池海水中汞的释放起到了重要的促进作用。研究结果有利于评价海水脱硫工艺的环境风险及其对局部区域大气质量的影响。As the absorbent of wet flue gas desulphurization(FGD) technology,seawater can dissolve oxidated mercury during the process of the removal of SO2 in flue gas,but in the process of aeration for the quality improvement of seawater,the mercury dissolved in seawater is inclined to release again.The method of gold amalgamation was employed to sample total gaseous mercury(TGM) in the air above the aeration sink,and the seawater in sink was also sampled to study the concentration and trend of mercury emitted from the aeration sink for the seawater-FGD in different operation conditions.The results showed that the average concentration of TGM was about 10.01 ng/m3,which was 20 times higher than that of local background,and it presented a positive correlation with mercury concentrations in seawater of the FGD system and aeration intensity.The experiment also found that the TGM concentrations in daytime,especially during noon time,were higher than those at night,which could be explained by that the photo-reduction played an important role on mercury emission from seawater in the aeration sink.The result of experiment is in favor of evaluating the environmental risk and the impact on local air quality caused by seawater FGD technology.中国科学院知识创新工程重要方向项目(KZCX2-YW-422-4

Retrospect and Outlook on Utilization of Fly Ash

介绍了粉煤灰的物理化学性质和结构,从不同角度分析了粉煤灰的应用情况及存在的问题,并对粉煤灰潜在的综合利用途径进行了探讨和展望,以期为粉煤灰的合理有效利用提供可行依据。Physical and chemical characteristics and structure of fly ash were introduced. Utilization situation and existing problems of fly ash were analyzed from different perspectives. And potential approaches of integrated utilization of fly ash were discussed to provide feasible basis for reasonable and effective application of fly ash

Experimental Study on Modified Activated Carbons for Elemental Mercury Adsorption

在小型固定床实验台上对中孔分子筛(SbA-15)、煤基活性炭(bPl)、不同含水量活性炭、苯酚和苯甲酸改性活性炭进行气态汞的吸附实验。结果表明:相对于中孔而言,微孔更有利于气态汞的吸附。负载羧基样品对气态汞的吸附能力与原始活性炭相比有很大提高。当羧基负载量为28.89Mg羧基/g活性炭时,样品对气态汞的吸附性能达到最佳;经酚羟基改性样品,其对气态汞的吸附能力显著降低,当达到吸附饱和时,原始活性炭的吸附量为306.55μg/g,而酚羟基改性样品最大吸附容量为133.1μg/g,且负载量与气态汞吸附量呈负相关,由此推测酚羟基对气态汞的吸附没有促进作用,而羧基有利于气态汞的吸附。活性炭表面存在适量水分有利于气态汞的吸附,当样品表面含水率为14.49%时,样品的吸附性能达到最佳。A laboratory-scale packed-bed reactor system was used to evaluate the capability of mesoporous molecular sieve(SBA-15),coal-based activated carbon(BPL),activated carbons containing different content of moisture,phenol-modified and carboxyl-modified activated carbons for mercury adsorption.The results show that compared to the mesopore structure,micropore structure on the surface of activated carbons is in favor of capturing mercury from carrier gas.The mercury adsorption capacity of carboxyl-modified activated carbons increases significantly compared to that of original carbons.And the best result obtained at the modification ratio of 28.89 mg carboxyl groups /g activated carbon.While the capacity of phenol-modified activated carbons for mercury adsorption decreases remarkably.When reaches saturation,the mercury adsorption capacity of original activated carbons is 306.55 μg/g,while the highest capacity of phenol-loaded activated carbons is 133.1 μg/g,and there is a positive relation between the amounts of phenol or carboxyl and mercury adsorption.It suggests that the phenol groups may have no effect on mercury adsorption,while the carboxyl groups are beneficial to the mercury adsorption.The presence of moisture on the surface of activated carbons can enhance their mercury adsorption capacities,and when the moisture content is 14.49%,the adsorption capacity reaches the best result.国家自然科学基金项目(20707018);福建省科技重点项目(2008I0024);福建省青年人才项目(2006F3118)---

PREPARATION of MODIFIED ACTIVATED CARBONS FOR MERCURY VAPOR ADSORPTION

采用高温热处理法去除活性炭表面含氧官能团,并通过化学浸泡法分别将酚羟基和羧基添加到活性炭表面。利用氮气吸附-脱附、X射线衍射分析、X射线光电子能谱法对改性前后活性炭进行表征。研究发现:经高温热处理的活性炭比表面积增大为1139M2/g,孔径集中分布于1nM以下;热处理后活性炭内部晶格结构更加完整。经过化学改性后,酚羟基和羧基均可以一定比例负载到活性炭表面,且比表面积随着负载量增多而下降。对气态汞的吸附实验表明:经高温热处理的样品对气态汞的吸附能力与原始活性炭相比有所下降:当达到吸附饱和时,原始活性炭的吸附量为306.55μg/g,而经热处理的样品的吸附量是243.5μg/g;负载羧基的活性炭样品,其吸附容量高达865.3μg/g;负载酚羟基样品的吸附容量为133.1μg/g。由此得出结论:活性炭表面的含氧官能团对其吸附气态汞有重要影响,其中羧基的存在有利于对气态汞的吸附,而酚羟基的存在对气态汞的吸附不起促进作用。The oxygen-containing groups on activated carbon surfaces could be removed by heating in nitrogen atmosphere (1 000 ℃ ).After heat treatment, carboxyl and phenol groups were added separately to the surface of activated carbons by chemical immersion method.And the surface physical-chemical properties of these carbons were characterized by nitrogen adsorption-desorption, X-ray diffraction and X-ray photoelectron spectroscopy.It was found that the BET surface area of the heat-treated samples was increased to 1 139 m2/g, meanwhile they had more ordered structures and more narrow pore size distribution which was smaller than 1 nm.After chemical modification, phenol and carboxyl groups could be loaded on the surface of activated carbons in a certain proportion, and the BET surface area decreased as the amounts of phenol and carboxyl groups increased.The experiments were conducted to evaluate the capability of original activated carbons, heat-treated and modified carbons on the adsorption of mercury vapor at room temperature.The results show that there is some decrease of mercury adsorption for heat-treated samples compared to original activated carbons.When it reaches saturation, the mercury adsorption capacity of original activated carbons is 306.55 μ g/g, while the capacity of heat-treated activated carbons is 243.5 μ g/g; the capacity of carboxyl-loaded activated carbons reaches 865.3 μ g/g, while the capacity of phenol-loaded activated carbons is 133.1 μ g/g.The assumption is that the oxygen-containing functional groups indicate significant effect on mercury adsorption ability of activated carbon.And the carboxyl groups are beneficial to the mercury adsorption, while the phenol groups may have no effect on mercury adsorption.国家自然科学基金项目(20707018);福建省科技重点项目(2008I0024);福建省青年科技人才创新基金项目(2006F3118

The Application of Fly Ash in the Eletroplating Industry

本文主要阐述了粉煤灰在电镀行业中的研究现状及应用状况,分析讨论了粉煤灰处理电镀污染物的机理,对比了现有的电镀污染物传统处理方法,并指出了粉煤灰在电镀行业应用中存在的问题及发展前景。In this paper,current research and application situation of fly ash in the electroplating industry is presented.Mechanism of treating elec- troplating pollutants by fly ash is discussed and analysised.In the end,current traditional treatment of electroplating pollutants is contrasted and existed problems and future look on the application of fly ash in the electroplating industry are mentioned